A vehicle powertrain typically includes an engine, a torque converter, and a transmission coupled in series, as well as a differential axle and sometimes a 4-wheel-drive transfer case. If the engine is an internal-combustion engine, the engine includes cylinders that serve as combustion chambers that convert fuel to rotational kinetic energy. The torque converter transmits rotational motion from the engine to the transmission while allowing slippage between the engine and transmission, for example, while the engine is running and the vehicle is stopped. The transmission transmits the kinetic energy from the torque converter to a drive axle and ultimately to wheels of the vehicle, while applying a gear ratio allowing different tradeoffs between torque and rotational speed. Overheating and other faults can cause the powertrain to malfunction and/or damage the powertrain.